title: Loss of caveolin expression in type I pneumocytes as an indicator of subcellular alterations during lung fibrogenesis.
abstract: Caveolin is a major structural protein of caveolae, also known as plasmalemmal vesicles, which are particularly abundant in type I pneumocytes and capillary endothelial cells of lung parenchyma. Here we demonstrate that caveolin expression in the alveolar epithelium of rats and mini pigs is strikingly downregulated after irradiation-induced lung injury. Indirect immunoperoxidase staining with polyclonal anti-caveolin antibodies, confirmed by double fluorescence studies with type I cell-specific monoclonal anti-cytokeratin antibodies or lectins, revealed a dramatic loss of caveolin immunoreactivity in type I pneumocytes. In contrast, caveolin expression increased in endothelial cells. Immunoblotting of lung homogenates from normal and irradiated rats using specific anti-caveolin antibodies confirmed the presence of caveolin in normal tissue and its marked decrease of expression in fibrotic tissue. The loss of caveolin as an important structural protein of caveolae in alveolar epithelial cells may be an early indicator of serious type I cell injury during fibrogenesis. The increase of caveolin immunoreactivity in endothelia of blood vessels may indicate that different types of caveolae and/or different regulatory mechanisms of caveolin expression exist.
authors.affiliation: Institute of Anatomy, Technical University of Dresden, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kasper
authors.forename: T
authors.initials: T
authors.lastname: Reimann
authors.forename: U
authors.initials: U
authors.lastname: Hempel
authors.forename: K W
authors.initials: KW
authors.lastname: Wenzel
authors.forename: A
authors.initials: A
authors.lastname: Bierhaus
authors.forename: D
authors.initials: D
authors.lastname: Schuh
authors.forename: V
authors.initials: V
authors.lastname: Dimmer
authors.forename: G
authors.initials: G
authors.lastname: Haroske
authors.forename: M
authors.initials: M
authors.lastname: Müller
mesh_terms: D000818:Animals; D015153:Blotting, Western; D051242:Caveolin 1; D022461:Caveolins; D005314:Embryonic and Fetal Development / Q000502:physiology; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000096:biosynthesis*; D011650:Pulmonary Alveoli / Q000378:metabolism* / Q000528:radiation effects / Q000648:ultrastructure; D011658:Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D013552:Swine; D013556:Swine, Miniature
chemical_list: C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D008565:Membrane Proteins